Zamboanga City, Philippines - Al-Qaeda-linked Muslim militants are the primary suspects in the bombing of a Catholic church and a coffee house in the southern Philippines over the weekend, officials said Monday.

No one was hurt in the pre-dawn attacks in Zamboanga City, 875 kilometres south of Manila, on Sunday.

Superintendent Jonathan Perez, city police director, said the bombs used in the two attacks were similar to those used in previous attacks by Muslim Abu Sayyaf rebels in the southern Philippines.

"There has been a threat in our area and the Abu Sayyaf rebels are the ones who could be behind it," he said.

Superintendent Jose Bayani Gucela, head of the police regional explosive ordinance and disposal unit, said the bomb that exploded at the Metropolitan Immaculate Cathedral compound was made from a 60-millimetre and 81-millimetre mortars attached to a digital timer.

The bomb was planted under a van parked inside the compound of the cathedral, and exploded less than one hour before the first Mass on Sunday.

Just 10 minutes later, another bomb made from 60-millimetre mortars and a mobile phone as a triggering device exploded in front of a coffee house at the ground floor of a building that also houses the local office of the Department of Foreign Affairs.

"The signature of the bombs are the same in previous attacks," Gucela said.

Security has been stepped up in Zamboanga City, strongholds of Abu Sayyaf rebels on Jolo island and Basilan province, in the wake of the bombings.

"We should not be scared," Zamboanga City Mayor Celso Lobregat said. "We should not give terrorists moral victory."

Lobregat assured residents that security forces were working overtime to capture the bombers and announced that the city government was prepared to give a cash reward to anyone who could provide information that would lead to the suspects' arrests. (dpa)